The non-iterative method with high precision is proposed for the pose estimation of uncalibrated in-camera parameters in incremental motion structure recovery. Based on the pinhole camera model, the equations which describes uncalibrated cameras pose estimation problems are given. The rotation matrix is parameterized by unit-norm quaternion, and then decomposed according to the four-fold symmetry. To eliminate variables properly and build a bivariate objective function, the least square principle and first order optimal condition is adopted respectively. An efficient solver by using the Gr bner basis technique is developed, so as to obtain optimal solution of rotation matrix and focal length. The complexity of proposed method is O(n). Experimental results prove the efficiency, high precision and numerical stability of the proposed solution.